In the manufacture of particleboard, which term is intended to cover chipboard and flakeboard, it is standard to compress a relatively thick mat by a factor of eight or more into a hard panel. The mat is soft and comprised of wood particles mixed with a phenolic or other binder. The finished workpiece is a hard board or panel with a pair of planar faces.
Such a panel is produced in a continuous press having a rigid press frame having vertically spaced upper and lower parts defining a press gap that can extend some 30 m. Upper and lower belts are spanned in the respective press parts between respective upstream and downstream rollers, at least one of which is driven to advance confronting upper and lower stretches of the lower and upper belts longitudinally through the press. Upper and lower press plates bear on the lower and upper surfaces of the upper and lower stretches of the lower and upper belts. Normally arrays of rollers run between each belt and the respective supporting plate to reduce friction.
The two belts typically are braced at an intake mouth of the gap against flexible intake members or plates. The mouth flares upstream. These intake members are typically braced against the press frame by hydraulic cylinders that are hooked to a common controller so that the shape of the intake mouth can be set centrally. Such systems are described in German patent documents 195 18 879 and in copending U.S. patent application Ser. Nos. 09/152,931 and 09/152,941.
In these arrangements, even when the actuators are secured at their ends by cardan joints, the intake plates and, hence, the belts passing over them, have perceptible bends at the actuators. These bends create points of excessive wear and subject the incoming mat to suddenly varying compression.